Path: utzoo!attcan!uunet!snorkelwacker!usc!jarthur!nntp-server.caltech.edu!tybalt.caltech.edu!toddpw
From: toddpw@tybalt.caltech.edu (Todd P. Whitesel)
Newsgroups: comp.sys.apple2
Subject: Re: APPLETALK AND MODEM PORT
Message-ID: <1990Jul9.194002.22422@laguna.ccsf.caltech.edu>
Date: 9 Jul 90 19:40:02 GMT
References: <9007091651.AA03831@apple.com>
Sender: news@laguna.ccsf.caltech.edu
Organization: California Institute of Technology
Lines: 24

SOMCYC@NUSVM.BITNET (Chiang Yao Chye) writes:

>Why is it that on the IIGS, you cannot have the modem port and AppleTalk both
>active at the same time?

First of all, you ARE plugging Appletalk into the printer port AND setting
slot 1 to "Your Card" ?? If you aren't then Appletalk doesn't know whether to
use the printer or the modem port because it thinks both are being used for
serial.

Second, and this is what you probably meant, they can't both be active at the
same time because every time a long Appletalk packet comes in, the appletalk
driver has to pull the whole thing from the serial port, and if more than
three characters come in from the modem then the modem port will lose them,
because the serial chip can remember the last three characters received but
no more than that. Since the longest Appletalk packet can be upwards of 10
9600 baud character times, this can cause some major character loss from the
modem. The real solution is to rewrite the SCC Manager so that characters from
both ports are received properly (I believe this is how the Mac's serial ports
are handled) -- I am pretty sure this is possible but it would have to do some
assembly experiments first.

Todd Whitesel
toddpw @ tybalt.caltech.edu